The U.S. military and America’s national security stands at the brink. This week, a congressional “super committee” was due to develop a plan to reduce the federal deficit by more than $1.2 trillion over the next 10 years. Failing to enact the plan by January 15, 2012, would result in automatic cuts to military spending–a scenario that Defense Secretary Leon Panetta describes as “devastating.”

The super committee’s ability to succeed remains in serious doubt, with reports of its deadlock and failure headlining newspapers this morning. Meanwhile, Republican presidential candidates are set to take the stage tomorrow night at Washington, D.C.’s Constitution Hall in a debate on foreign policy and national security co-hosted by The Heritage Foundation and the American Enterprise Institute. With the future of America’s national security hanging in the balance, the question of which presidential candidate would best protect America has more importance than ever.

In letters sent to Senators John McCain (R-AZ) and Lindsey Graham (R-SC) last week, Panetta detailed the danger of further defense cuts if the super committee fails to meet its target. Panetta said that under the worst-case scenario, “the total cut will rise to about $1 trillion compared with the FY 2012 plan,” which in practical terms means “the smallest ground force since 1940, the smallest number of ships since 1915, and the smallest Air Force in its history.”

And amidst these potential reductions to U.S. forces, Panetta wrote, “Unfortunately, while large cuts are being imposed, the threats to national security would not be reduced. As a result, we would have to formulate a new security strategy that accepted substantial risk of not meeting our defense needs.” Tragically, America’s military is being threatened despite the fact that national defense is the priority job of the national government, as set forth in the U.S. Constitution. The Defending Defense Project lays out three key facts about military spending today that the GOP presidential candidates should bear in mind as they seek the White House.

First, the main driver of America’s growing debt and deficit is domestic spending–especially entitlement spending–and not defense spending. Mandatory and discretionary domestic program spending has experienced almost exponential growth since the 1970s, contrasted with spending on national defense, which has stayed comparatively stable.

Second, defense spending has been subjected to several rounds of reductions under President Obama, with long-term cuts amounting to roughly $850 billion already. Heritage’s Mackenzie Eaglen debunks the myth that the military hasn’t already faced cuts:

Using Washington math, some say there have been no defense cuts. But President Obama’s started slashing military plans and priorities since taking office. His first defense budget canceled or delayed some 50 major equipment programs, including ships, missile defense, cargo and fighter aircraft, and ground vehicles valued at more than $300 billion. Then, behind the scenes, the White House took another $78 billion out of the military’s budget last winter.

Eaglen writes that Obama was so pleased with these defense cuts that he vowed to repeat them by cutting another $400 billion from the military. If Congress fails to pass into law a massive deficit-reduction bill as required, then long-term defense will be again cut–this time, by as much as $500 billion.

The third fact? In order to maintain global leadership, the United States must make commensurate investments in defense of its national security and international interests. Heritage’s Jim Talent explains why that mantle of leadership is so crucial:

Ever since the end of World War II, American power has been the chief deterrent to aggression: the shield under which the tools of diplomacy, trade, and engagement have produced unprecedented progress toward freedom and democracy. But the shield is cracking. America’s global influence is being checked and rolled back, and even the homeland is no longer safe from attack.

The United States continues to face threats at home and abroad, yet slashed military spending would undermine America’s ability to confront these challenges. America’s debt and rampant spending are serious problems that needs to be addressed, but eviscerating the military–which has already been cut–is not the way to do it.